This invention relates generally to gas turbine engine components, and more particularly to apparatus and methods for placement of holes in rotating engine components.
A typical gas turbine engine includes multiple high-speed rotating parts, for example one or more compressors interconnected to one or more turbines by shafts. The rotating components experience large centrifugal forces generating stresses therein.
Such rotating components often include mechanical features such as a holes and other discontinuities. As is known in the art, each of these features creates a stress concentration that increases local stresses in the component.
In particular, some “hot section” components such as rotating high pressure turbine (“HPT”) blades operate in an extremely high temperature environment. To ensure adequate service life, the blades are hollow and are provided with a flow of coolant, such as air extracted (bled) from the compressor. This coolant flow is circulated through the hollow airfoil's internal coolant path, typically including internal crossover holes, and is then exhausted through a plurality of cooling holes. HPT leading edge crossover holes are formed by a ceramic core as part of a casting process. HPT leading edge crossover holes are typically oriented along the splitline of the core die used to manufacture the core, in order to reduce manufacturing complexity. The result may not be optimum for minimizing stress in the crossover holes.
Accordingly, there is a need for a rotating turbine component incorporating holes, where the additional stress due to the inclusion of the holes is minimized.